Development And Application Of A Hyperspectral Polarimetric Sun Photometer

Sun photometer is a kind of ground-based solar radiation observation equipment,its by measuring the solar radiation that reaches the surface,measure the degree of atmospheric extinction,and inverse performance of a variety of atmospheric parameters,because of its atmospheric aerosols and other atmospheric parameters have high observation accuracy,in the atmospheric environment,atmospheric meteorology and other fields have important applications.At present,China’s ground-based commonly used is the channel type sun photometer,its observation of radiation is limited by the narrow band filter,can only obtain a number of specific band of solar radiation information,has not been able to cope with the current integration of space and sky on the demand for hyperspectral observation of solar radiation.In this paper,we develop a solar photometer that can simultaneously acquire solar radiation with high spectral resolution information in the 340～2100nm band,and is equipped with a polarisation channel to acquire polarisation information of scattered light from the sky.The details of the study are as follows.(1)In the architecture design of the sun photometer,two optical fibre spectrometers are used to achieve high spectral measurement of solar radiation in the 340～2100nm band by spectral splicing,and a low stray light measurement optical path is designed.On this basis,an ARM chip is used as the independent master control of the sun tracking turntable,and a combination of programmed tracking by the sun position algorithm and active tracking by the CCD four-quadrant detector is designed In order to ensure the stability of the instrument and its adaptability to the environment,a dual-probe temperature collector is used to obtain the internal and external temperature of the instrument in real time,and a programmable relay and cooling and heating module are used to realise a programmable temperature control system.to determine whether there is cloud cover or not.(2)Based on LabVIEW platform for the sun photometer to develop a set of upper computer control program,the use of multi-thread control to achieve independent communication between the modules,the program to days for the cycle of automatic control of the sun photometer,mainly to achieve fully automatic measurement of direct solar radiation and data storage,the system temperature control and real-time display of the instrument operating parameters,and for the program to design a friendly UI interface,with the Windows system industrial computer as the carrier of the program,can be achieved through the network to the sun photometer system of remote monitoring and data interaction.(3)Proposed a spectrometer noise suppression algorithm,through the algorithm to simulate the real-time noise of the instrument to replace the traditional use of physical masking to obtain noise,improve the real-time observation accuracy and observation efficiency;combined with the Langley method and laboratory standard light source calibration to complete the sun photometer direct channel full-band irradiance calibration,to make up for the Langley method in the gas absorption band calibration accuracy is low Finally,the application of the sun photometer is studied,and the spatial and temporal distribution characteristics of atmospheric aerosols are analysed by inversion through the measurement and analysis of direct solar radiation and atmospheric transmittance in external field experiments,and the polarisation characteristics of sky scattered light are observed through the polarisation channel.